Thursday, January 24, 2019

A3S Assembly Notes for a Friend

I recently sold one of my reconditioned Cushcraft A3S antennas to Keith K6POC and wanted to take a few pics to help him with assembly. I'm posting them in my blog because it's easier to put the notes together for him to access, and maybe it'll help one of y'all sometime while assembling a similar antenna. This antenna was originally bought back around 1975 by a good friend K4CMH (now SK). I got it from him in the early 90's and rebuilt it for my own tower. I have now installed a Force 12 6el HF yagi, so I rebuilt it with new SS hardware, a few dimensional changes, and updated it with my longer lasting heat shrink trap caps. 



The traps were all disassembled, cleaned, internal connections tightened, checked with the grid drip meter, and tagged.


Cushcraft uses 3 different types of traps in this antenna, they call them TA, TB, or TC for trap type. The old stickers they put on the traps when mfg were long gone, so i marked them and tagged them with new labels later...

I've rebuilt a number of Cushcraft A3 and A3S antennas over the years. (The "S" just means Stainless Steel hardware). Cushcraft marks them with invisible ink (just kidding), so you're on your own if you mix the traps up on an older antenna. Turns out it's not too tough to figure out. Also, those crazy little plastic caps that go on the ends of the traps don't hold up very well, and I've found that 2" heat shrink seems to last a lot longer (and is cheaper to boot!).

I've uploaded a few bits and tips to my site that might help, in case you find yourself trying to identify the traps or rebuild one of these. One is a .pdf from Dale KG5U, one is a .txt file with my tips, and a .jpg pic of a trap with the heat shrink end caps. Hope that helps some of you!!

Go to my website at http://www.WB4IUY.net , mouse over [Workshop]. and select "Schematics Manuals". Scroll down to the Cushcraft section and you'll find it. 




I wound two different types of coils for coupling to the traps..one style for inserting into the trap, another type for slipping over the trap stub...



This is the guy I get this heat shrink from... good stuff, VERY UV resistant. 

 
The pic of one end of a trap with the new heat shrink cap on. NOTE** the end of the trap that has a screw that connects the outer shell of the trap to the stub ALWAYS goes towards the boom....


I cleaned all this old oxidation from the original steel clamps off the metal while reconditioning it. I use a wire brush and small belt sander. 


Traps and couplers ready for assembly...


The center spreader of the director and reflector assembly is mild steel, so I remove all rust and oxidation and cold galvanize it. The last one I did still looked good after 25 years in the sky!


Fresh cold galvanizing in place...


Take note, the director, driven and reflector center sections are grouped together. I marked the slide-in sections with black tape for ease of assembly. Just slip them in to the tape, and tighten the clamps. Lengths are correct. 


Director assembly bundled together...


Reflector assembly bundled together... 


New driven element composite center  insulator. I like this better than the fiberglass version that gets all frayed out in the sun...


The boom is separated on one side from the center coupler for shipment. Slip it back together to the black tape and tighten the clamp. 


Boom disassembled for shipment...


I marked the boom where the director, driven, and reflector assemblies should reattach.  This is the reflector point..


Driven element attaches here...


Director attaches here...


All traps are tagged per TA, TB, or TC version. 


Reflector traps assembled in the proper order and length...



Driven traps assembled in the proper order and length... 



I wrote DOWN on the bottom of the traps near the drain holes. Make sure those holes are always facing down when the antenna is assembled...



Director traps assembled in the proper order and length... 


Driven element..one side of coax connects here...


Driven element, other side of coax connects here...


Driven element all taged and ready for assembly. Slip the ends pieces in to the black tape bands and tighten the clamps. 


Big load of aluminum all finished and on the way to Ca. Enjoy it, Keith!